Rotary drilling-bit.



L. L. RICHARD.

ROTARY DRILLING BIT.

APPLICATION FILED AUG-15.1916.

Patented May 15, 1917.

WITNESS INVENTOR. 7' fiw/M A TTORNE Y.

I 15 the bit, the point portionsmust be drawn ting e ges are dressed. The dotted lines 70 siren snares rarnnr @FFME.

LEROY L. RICHARD, F COALINGA, CALIFORNIA...

ROTARY DRILLING-BIT.

1,226,33'7 Specification of Letters Patent. Pa tenib gdl May 15, 1191?, Application filed August 15, 1916. Serial No. 115,014..

To all whom it may concern: of Fig. 4. Fig. 7 is a cross-section of modi- Be it known that I, LEROY L. RICHARD, fied form; and Fig. 8 is a cross section of a citizen of the United States, residing at still another modified form, all falling with- Coalinga, in the county of Fresno and State in the scope of my invention.

of California, have invented certain new Referring first to Figs. 1, 2 and 3, which 0 and useful Improvements in Rotary Drillshow the ordinary form of fish-tail bit,

ing-Bits, of W rob the following is a specithe numeral 1 is the bit, usually made of cation. chrome steel, and having the middle demar- My invention relates to rotary hydraulic cation depression 2 of the oppositely diver- 1o drilling bits of the fish-tail type. gent cutters 3. This bit, as shown in Fig. 3,

In thistype of bit the wear is much has a uniform thickness throughout its greater on the points of the cutters than on width. theirremaining portions, resulting in such In Fig. 1, the lines A, B, C, indicate the a distortion of contour, that in redressing shape or contour to which initially the cutdown from the metal of the sides or edges a B 0 show the effect of the wear on the bit. from which they are developed, and the in- The dotted lines a b 0 show the shape to termediate portions must be cut away, in which the bit is drawn at the next dressing. order to restore the proper contour. In bringing it to this shape it is necessary 20 In the ordinary form of bit of this type, to draw out the points a a d and c c e and Which has a uniform thickness throughout to cut away the shaded portion d b e B. its width, except for the slight depression This shaded portion represents a waste of in its middle which marks and defines the material at each dressing of the bit, as well meeting limits of the cutters and provides as the waste of labor in cutting it away. In 25 for their opposite angle separation, the order to avoid as much of this waste as posdrawing down of their points in redressing sible, the points a and c are drawn down to weakens them and the material above; and an extent that weakens the bit at the point the cutting away of the intermediate porwhere the greatest strain and wear occurs. tions from the relatively thick stock is a In order to overcome these disadvantages 30 Waste of material and labor. I make my bit initially as shown in Figs. 4, The object of my invention is to overcome 5 and 6. The bit 4: has a cross section as these disadvantages; and this object I 'atshown in Fig. 6, in which the metal is so tain, by making the bit initially thicker in distributed as to be made available to reits side or edge portions from which the place the wear with the least possible labor 35 points of the cutters. are developed, and and waste of material. Since the wear is thinner in its intermediate portion from greatest at the points A and C of the cutting which the remainder of the cutters is deedges and less toward the center, I make the veloped. By this I provide abundant matebit thicker at the sides or edges, from which rial from which to develop the points in the points A and C are developed and thin- 40 successive redressings, and meager material ner toward the center along the portions to cut away in developing the remaining porfrom which the remainder of the cutters is tions of the cutters. to be developed in redressing.

In order to fully convey an understand- This conformation in cross section may ing of my invention, I deem it best by illus assume a variety of forms, not only that of 45 tration to first show diagrammatically the Fig. 6, but also, for example, that of the bit ordinary fish-tail bit and the disadvantages 5 of Fig. 7 or of the bit 6 of Fig. 8. above mentioned, and then to illustrate my The advantages of this general form are improved bit for comparison. as follows:-The loss of material and labor Accordingly, in Figures 1 2 and 3, I show entailed in cutting away the shaded portion respectively a front elevation, a side eled b c B in Fig. 1 is avoided or reduced to vation and a cross section on the line 33 a minimum. The portions a a (Z and c c e of Fig. l, of the ordinary bit of this type. can be drawn out to the proper shape with In Fig. 4 I show a front elevation of my less labor. 1 Owing to the thickness of the improved bit. Fig. 5 is a side View of the bit at the edges, these points are not weak- 55 same. Fig. 6 is a. section on the line 66' ened by this operation, and will not wear or The cost of manubreak away so quickly.

than that of the stock having on each face a central longitudinal depression, the lower edge of said stock being symmetrically curved from each side upwardlyto said depressions and lts lower end from said depressions to each side being symmetrically bent in opposite direc- 20 tions to form the cutters, and said stock throughout its length being thicker at its sides than the portion intermediatesaid sides.

In testimony whereof I have signed. my 25 name to this specification in the presence of two subscribing Witnesses.

LEROY L. RICHARD.

Witnesses:

A. S. TAYLoR, S. G. HUGHES. 

